It was very early days in Bitcoin when each transaction was required digital signature to verifies the transaction on blockchain which captured additional space on chains. In early 2015 developers in core team of Bitcoin proposed to remove this signature from transaction. Because they think that by removing this unnecessary signature we will save space on blockchain and enable network to perform more transactions on same block. 

This Idea works and segregated witness or Segwit term introduced. The SegWit upgrade was proposed in 2015 by a group of Bitcoin developers as a way to address the scalability problem of the Bitcoin network which was struggling to handle the increasing number of transactions being processed.

The SegWit upgrade involves changing the way that transactions are stored on the Bitcoin blockchain. Currently each transaction includes a signature which takes up space on the blockchain. With SegWit, the signature is removed from each transaction and replaced with a separate "witness" section that includes information about the transaction.

This change allows more transactions to be included in a single block which increases the overall capacity of the network. It also makes it easier for users to create complex transactions, such as those that involve multiple inputs and outputs.

SegWit was first implemented in 2017 and has been widely adopted by the Bitcoin community. It is considered an important step towards improving the scalability and efficiency of the Bitcoin. 

The transaction speed of Max. 20/second only came possible after that induction of Segwit term. It helps in both ways as more transparency in transaction to get the confidence of user because it starts saving his time and other side produced Extra space on blocks to perform more transactions.

The fork of Bitcoin in halving of 2018 emerged as Bitcoin Cash (BCH) which has bigger block size and totally signature free which allow it to perform much bigger number of Transactions/ second. Same time accepted next halving in June 2024 will generate more accuracy, Speed and lowest fee structure. 

Cheers,

Amjad